Dynamic duo: Understanding the interplay between fatigue and freeze-thaw in concrete durability

Abstract

In cold climates, pavement deterioration is significantly influenced by the dynamic duo of freeze-thaw cycles and fatigue loading, compounded by cyclic environmental stresses. This study examines their combined effects on concrete pavement degradation, focusing on microstructural changes and durability. Mechanical properties, including compressive strength, ultrasonic pulse velocity, porosity, and mass loss, were analyzed, alongside SEM and EDS evaluations. Results reveal that the dynamic duo causes more severe damage than individual or combined loading. Fatigue loading generates microcracks, while cyclic freeze-thaw stresses degrade the interfacial transition zone (ITZ), increasing porosity and reducing compressive strength up to 30 %. Elemental analysis shows an elevated calcium-silicon (Ca/Si) ratio, indicating microstructural weakening. Coupling actions reduce fatigue life by up to 75 %, and ultrasonic velocity tests show a 5 % reduction, highlighting intensified internal damage. Porosity and mass change increase significantly with repeated fatigue and coupling actions. Unlike previous studies that typically treat fatigue and freeze-thaw stresses in isolation or through sequential testing, this research introduces a novel coupled experimental approach to simulate the real-time interaction of mechanical and environmental loads. These findings mandate an urgent paradigm shift in cold-region pavement design: current practices significantly underestimate coupled damage effects, necessitating new interaction-based durability models and revised safety factors for realistic performance prediction under concurrent mechanical-environmental loading. © 2025 Elsevier Ltd